For as a gold refiner having cast a piece of gold into the furnace allows it to be proved by the fire until such time as he sees it has become purer, even so God permits the souls of men to be tested by troubles until they become pure and transparent and have reaped much profit from this process of sifting: wherefore this is the greatest kind of benefit.
Let us not then be disturbed, neither dismayed, when trials befall us. For if the gold refiner sees how long he ought to leave the piece of gold in the furnace and when he ought to draw it out, and does not allow it to remain in the fire until it is destroyed and burnt up, much more does God understand this, and when He sees that we have become purer, He releases us from our trials so that we may not be overthrown and cast down by the multiplication of our evils. Let us then not be complaining or faint-hearted when some unexpected thing befalls us; but let us allow Him Who knows these things accurately to prove our hearts by fire as long as He pleases: for He does this for a useful purpose and with a view to the profit of those who are tried.
Saint John Chrysostom
On the Two Paralytics in the Gospels
Homilies on Profitable Subjects